Process for treating textile fabrics



United States Patent 3,390,464 PROCESS FOR TREATING TEXTILE FABRICS Charles R. Sheehan, Williarnsburg, Va., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware N0 Drawing. Filed June 28, 1965, Ser. No. 467,744

6 Claims. (Cl. 34-13) This invention relates to the treatment of textile fabrics and more particularly to the heat treatment and setting of textile fabrics made from synthetic fibers.

It is well known that in the past the handle and appearance of fabrics have been improved and their finish has been set by the use of decating or 'decatising machines and processes. In general, these processes comprise winding the fabric to be treated on a perforated roller, with or without an apron, and thereafter either immersing the roller carrying the wound fabric in hot water or flowing steam through the fabric by way of the perforations in the roller. The machines commonly used comprise, in essence, a rotatable perforated roller or drum on which the fabric may be wound, together with a carrier apron employed to carry and exert pressure on the wound fabric, and means to pass heated water or steam into the interior of the perforated drum so that it may flow through the perforations and through the fabric. In some arrangements there are also provided means for applying a vacuum to the inside of the drum or roller whereby air may be drawn through the fabric, in a reverse flow to that of the hot water or steam treatment so as to cool and dry the fabric quickly.

These decatising processes and machines have been widely and successfully applied for example in the treatment of worsted fabrics made from natural fibers such as wool, with with the advent of fabrics made from fibers of polyamides, acrylics and polyesters and the like, it has become apparent that the temperatures obtained by using steam or hot water are inadequate to have a durable 'heat setting effect on the synthetic fibers.

It is an object of this invention to overcome the disadvantages of the prior art and to provide a new and improved method for heat treatment of textile fabrics.

Other objects and advantages of this invention will be apparent from the following description.

According to this invention it has been found that fabrics made from fibers of synthetic materials may be stabilized with respect to shrinkage during processing and also after they have been made into garments and the like if they are subjected to a heat setting before or after processing, preferably on a decating machine, at an elevated temperature which is fairly close to but below the stick or softening temperature of the synthetic fibers, and thereafter rapidly cooled.

It has been found, according to this invention, that although the heat applied to the synthetic fabrics should not equal or exceed the normal stick, shrink or softening temperature of the fabric, the best results are obtained if heat is applied by passage through the fabric of a gas at temperatures up to a maximum temperature of about 10 to 100 F. below the stick, shrink or softening temperature of the synthetic fiber with about a 90 F. differential being preferred.

Thus, for example, in the case of polypropylene fabrics, i.e., fabrics made from fibers of polypropylene which have a shrink temperature of about 167 F., hot air at 150 F. gives excellent setting and finishing effects when following the practice of this invention. As another general illustration, when fabrics made from the polyamide fiber known as nylon 66, which has a softening point of about 460 F., are heated with hot air at about 440 to 450 F., followed by rapid cooling, according to the process of this invention excellent results are obtained.

3,390,464 Patented July 2, 1968 "ice The following examples will further illustrate, in more detail, how the invention may be practiced.

Example I A polyamide, woven stretch fabric having a softening temperature of 460 F. was placed upon and then carried by a feed apron and wound around a perforated steaming drum or roller in a conventional decating machine. Thereafter heated air, at a temperature of 375 F., was passed for 1.5 minutes into the interior of the drum and, by way of the perforations in the drum, passed through alternate layers of apron and fabric. Following this hot air treatment the resultant heat-set fabric was removed from the drum and laundered at F. and then tumble-dried at F. and found to have retained its smooth, pressed feel and appearance. When the same fabric was treated in the same apparatus and in the same way but while using steam (212 F.) the material was found to have lost its smooth, pressed feel and appearance after laundering and tumble-drying as previously outlined.

Example 11 An acrylic, core-spun Spandex (elastomeric fiber) blend, double-knit fabric having a softening temperature of 465 F. was treated exactly as described in the case of Example I except that the hot air, at 375 F., was passed through the fabric for two minutes. Upon removal from the drum, followed by laundering and tumble-drying as described in Example I, the fabric was found to have retained its smooth, pressed feel and appearance. When the same fabric was similarly treated with steam (212 F.) the material was found to have lost its smooth, pressed feel and appearance after laundering and drying.

Although reference has been made in the foregoing description and examples to the use of heated air as the gas employed for heating the fabric, it has been found that other gases such as super heated steam and nitrogen may also be satisfactorily employed. As a matter of fact, nitrogen has been found to be preferred in case of some synthetics such as some nylons which may exhibit a tendency to discolor if treated with heated air alone.

In order to assure the setting or retention of the desired dimensional stability of the synthetic fabrics, it is preferred, according to this invention, to follow the relatively short heating on the perforated drum, as previously described, with a cooling step of substantially the same duration as the heating step. To illustrate, by reference to Examples I and II, after 'heated air is passed for 1.5 and 2 minutes, respectively, through the fabrics disclosed in these examples, room temperature air can be passed through the fabrics, to cool them rapidly, for substantially the same periods of time as was taken for the heating steps.

Generally speaking, it has been found that normally the advantages of this invention may be obtained by the use of relatively short heating times, passage of the heating gas through the fabric being necessary for period-s of less than three minutes ordinarily in order to accomplish the desired dimensional stability or settingof the fabric when followed by approximately the same length of cooling time. Preferably the heating and cooling periods are from 1.5 to 2 minutes in duration.

Various changes and modifications may be made in the practice 'of this invention without departing therefrom or sacrificing the advantages thereof.

What is claimed is:

1. A process for heat setting and dimensionally stabilizing fabrics made from synthetic fibers which comprises heating such fabrics in a pressed state by passage therethrough of a heated gas at a temperature from 10 to 100 F. below the softening temperature of the synthetic 6. The process of claim 1 in which the heated gas is material and thereafter rapidly cooling the treated fabric passed through the fabric for from 1.5 to 3 minutes. by passage therethrough of a cooling gas.

2. The process of claim 1 in which the heated gas tem- References Clted perature is 15 90 F. below the said softening tempera- 5 UNlTED STATES PATENTS 'ture.

- 2,473,823 6/1949 Sands 34-42 airS. The process of clalm 1 1n which the heated gas 13 2,807,097 9/1957 Kullgren et a1.

4. The process of claim 1 in which the heated gas is 5/1966 Jarkow 34 60 X super heated steam. 10 1: 1- 4 5. The process of claim 1 in which the heated gas is FREDERICK MATTLSON Plmmly nitrogen. JOHN J. CAMBY, Examiner. 

1. A PROCESS FOR HEAT SETTING AND DIMENSIONALLY STABILIZING FABRICS MADE FROM SYNTHETIC FIBERS WHICH COMPRISES HEATING SUCH FABRICS IN A PRESSED STATE BY PASSAGE THERETHROUGH OF A HEATED GAS AT A TEMPERATURE FROM 10* TO 100*F. BELOW THE SOFTENING TEMPERATURE OF THE SYNTHETIC MATERIAL AND THEREAFTER RAPIDLY COOLING THE TREATED FABRIC BY PASSAGE THERETHROUGH OF A COOLING GAS. 